The 175-m-long quay long wall in Durban has been completed. The project which was overseen by geotechnical contactor Franki Africa with a draft of 12.m is for marine engineering company Dormac’s new floating dock.
Paul Pearce, Franki KwaZulu-Natal’s branch manager highlighted the demand of creativity in solutions to complex challenges. He said, ”Our quay wall proposal of continuous flight auger piles and jet grout columns gave us the advantage we needed to secure the contract.”
The existing site left a lot to be desired with a functioning slipway with a heavy framework of metal beams forming a foundation used for ship repair. Pearce says that although a diaphragm wall structure had been contemplated during 15 years of practicability studies, Franki’s alternative had proved to be more economical and less time consuming.
Moreover, their credibility was further boosted by the fact that even after a delay in contract approval which would trickle down to the amount of time used for construction, Franki readily took up the challenge as well as an incentive to complete the works early. Failure to meet the deadline would have not only affected their work but also the transport as shipping, being a renown industry for tight schedule and high operational costs would have incurred heavy losses.
Pearce singles out the cooperation between Franki and Keller Germany as the most helpful in terms of specialized geotechnical skills for the successful outcome. He further added that the jet grouting required top-end management, operators and support which requires the operators three week’s worth of training and testing. Additional equipment was sourced from Europe.
Some of the challenges faced was the working area; the edge of Durban harbor exposed the workers to unpredictable tidal conditions. Subsequently, the Franki crew had to work round the clock in order to accommodate the same.
In order to ensure a vertical face to the quay wall by getting the positioning correct, Frankis’s works department were forced to manufacture custom-built guides and frames to help align piles with the tolerances.
Franki also had to increase the piling production to meet Dormac’s request to complete the contract earlier. Franki’s decision to construct the 3-m-deep reinforced capping beam while incorporating the tie bars as well as the hanging of the precast fender panels, created an aesthetically pleasing and erosion-resistant face to the quay wall.